Explanations for cross-national divergence in attitudes towards precautionary regulation have largely neglected the potential influence of legal traditions, notably the tension between precautionary tools and the common law’s reactive approach. This is partially due to the apparent clash between this thesis and the early emergence in Britain of precautionary regulation under the 1863 Alkali Act. Historical accounts of this development have focused entirely on domestic factors, entrenching in the process an understanding of the Alkali Act — and Britain more generally — as the origin of centralised precautionary environmental regulation. In contrast, this article argues that the Act was directly inspired by French and other continental regulatory models, and that the regime it spawned constituted a continental-common law hybrid. If the Alkali Act regime was partially transplanted from the Continent, it becomes easier to reconcile the civil law character of precautionary regulation with the evident presence of that instrument in Victorian Britain.